Trying to push a new contact list via the API and keep hitting a 400 INVALID_VALUE error. The UI works fine, so I know the data is valid. Here is the payload I am sending:
POST /api/v2/outbound/contactlists
{
"name": "Test List 001",
"type": "IMPORT",
"contacts": [
{
"columns": [
{"id": "phone_number", "value": "+491234567890"}
]
}
]
}
The response just says the value is invalid without pointing to a specific field. I have checked the timezone and encoding. Nothing stands out.